The subject matter disclosed herein relates to aircraft environmental control. More specifically, the subject disclosure relates to an inlet shroud of a ram air fan for an aircraft environmental control system.
Many types of aircraft use ram air flow for various purposes, such as in cooling systems for the aircraft. For example, the ram air flow may be utilized to remove heat from various aircraft lubrication and electrical systems and/or used to condition aircraft cabin air. When the aircraft is in flight, movement of the aircraft creates a sufficient source of ram air flow which can be used for the purposes described above. When the aircraft is on the ground or is operating at low speeds, a ram air fan is typically utilized to increase air flow to the cooling systems. Such a ram air fan is driven by an electric motor which, in turn, must be cooled by air flowing across it. Cooling flow is drawn at a heat exchanger inlet and across the electric motor to a ram air fan inlet. The flow of cooling air, and thus the performance of the electric motor and ram air fan, is typically limited by a pressure drop from the heat exchanger inlet to the ram air fan inlet. A balance must be achieved between this pressure drop, which can impact heat exchanger performance, and providing sufficient cooling flow to the electric motor and other components of a ram air fan assembly.